Merriam-Webster Visual Dictionary, Drilling-Rig Entry.
http://visual.merriam-webster.com/energy/geothermal-fossil-energy/oil/drilling- rig.php

 

Lapeyrouse, Norton J. Formulas and Calculations for Drilling, Production and Workover. New York: Elsevier, 2002. Print.

 

Schlumberger Oilfield Glossary

http://www.glossary.oilfield.slb.com/default.cfm

 

Encyclopedia Britannica, Petroleum Entry

http://www.britannica.com/EBchecked/topic/454269/petroleum

 

USGS, Seepage Effects on the Natural Environment

http://geomaps.wr.usgs.gov/seeps/environment.html

 

Picture of Spindletop, Texas Blowout

http://green.blogs.nytimes.com/tag/oil-rig/